RuntimeError: MPU6500 not found in I2C bus.

[varna9000]

Hi, I've wired the sensor to nodemcu esp8266, however the library si giving me the following error:

Traceback (most recent call last): File "<stdin>", line 6, in <module> File "mpu9250.py", line 39, in __init__ File "mpu6500.py", line 103, in __init__ RuntimeError: MPU6500 not found in I2C bus.

Wiring: CLK->pin D1, SDA->pin D2.

i2c scanner shows:

Scan i2c bus... i2c devices found: 1 Decimal address: 104 | Hex address: 0x68

I'm using MicroPython v1.12 on 2019-12-20

What could be wrong?

[tuupola]

You could try to debug what whoami register contains.

https://github.com/tuupola/micropython-mpu9250/blob/master/mpu6500.py#L102

[varna9000]

Can you give me a clue how can I do that? I'm not that much into registers :) The board I'm using is this:

https://www.tinytronics.nl/shop/image/cache/data/product-493/mpu-9250-1000x1000.jpg

I tried to find a Datasheet for this particular board and find the whoami register value, but there is no definite information anywhere. Is there a way to query the board and check it?

[varna9000]

Ok, got some progress. I printed self.whoami and the hex which came out is 0x70. So this works fine now when I replaced your default 0x71. Now same problem is with ak8963.py:

Traceback (most recent call last): File "", line 10, in File "ak8963.py", line 76, in init File "ak8963.py", line 140, in whoami File "ak8963.py", line 198, in _register_char OSError: [Errno 19] ENODEV

Will try same approach and report back here.

[varna9000]

I think, this board doesn't have a magnetometer.... should i2c scan return ak8963 address as well?

[tuupola]

Quickly Googling the MPU-92/65 breakout board you have, should have the MPU-9250. MPU-9250 is a System in Package (SiP) which combines two chips: MPU-6500 and an AK8963.

The value of MPU-9250 WHO_AM_I register is 0x71 and address is 0x68 or 0x69. The value of MPU-6500 WHO_AM_I register is 0x70 and address is 0x68 or 0x69. So if I am reading my code correctly you just found a bug. I seem to have a wrong value. I don't really understand why I have not caught this before.

To directly access the magnetometer it has to be in bypass mode. Bypass mode is enabled at mpu6500.py#L112-L115. AK8963 address should be either 0x0c, 0x0d, 0x0e or 0x0f depending on the configuration.

So maybe your breakout board only has the MPU-6500. Other option is that the bypass mode is not working for some reason. You could try checking with magnifying glass what the chip on the breakout board is.

[varna9000]

As far as I can read, chip ID is MP65 6799D1 L1506 I'll try to find a Datasheet and also I'll check also the addresses you mentioned and see if I can get the magnetometer (if any) to work.

Edit: Just tested all addresses 0x0c, 0x0d, 0x0e and 0x0f by entering them manually here:

https://github.com/tuupola/micropython-mpu9250/blob/master/ak8963.py#L67

but none of them works. Also I couldn't find anything about this chip...

[tuupola]

MP65 suggests the chip is the standalone MPU6500. Also the WHOAMI value suggests it is the standalone MPU6500 and not the MPU9250 SIP. In other words it does not include the magnetometer.

I have only been testing with MPU9250 which was why I did not catch earlier that the standalone accelerometer has different WHOAMI value. Will commit a fix soon. Thanks for the heads up!

[tuupola]

You should be able to use the standalone MPU6500 witch something like following:

from machine import I2C, Pin
from mpu6500 import MPU6500

i2c = I2C(scl=Pin(22), sda=Pin(21))
sensor = MPU6500(i2c)

print("MPU6500 id: " + hex(sensor.whoami))

[varna9000]

Using only MPU6500 class, chip works perfect :) Thanks for the great library!